Digital Thermometers

[schutzen]

The infrared/laser thermometer is an excellent idea. We use them at work for a multitude of diagnostic checks. However, I have had poor luck with Sears Craftsman tools. Not the hand tools, but anthing that is electrical or electronic. I have a year old Craftsman battery charger in my shop. I used it 5 times and it is toast. Did I misuse it? I don't think so, my "cheap" old Schumacher charger on lasted 17 years. My daughter gave me a Craftsman Laser Level for my birthday. I used it twice. The laser is fine, but the sprit fluid has evaporated/drained from the leveling vials. No, I didn't drop it and it was stored in the case. Even it they replace them "free", it still takes time to replace something that should have been made correctly in the first place.

Check with NAPA for an infrared thermometer, they had them on sale for $49.95 last month. I have had good luck with their tools.

Just my two cents worth.

[upperb]

Again, thanks to all of you for your thoughts and advice.

Mouldsmith: No need for apologies. I type with 2 fingers (sometimes 3) and more than once have lost a document it took me a half-hour to type! I know the feeling!

[AZ-Stew]

Two items:

The Harbor Freight thermocouple thermometer probe will work for immersion in the pot. You gotta bend the wires a bit to get it to stay in one place, but I guess what I really should do is make a little metal clip for it so it doesn't move. It's interesting to watch the display as you move the thremocouple around to different spots in the pot. Which brings me to item 2...

Taking a reading from the top of the pot will not tell you what the temp is at the bottom (for bottom-pour casters) or in the middle (for the dippers). The temperature can be (if I recall correctly) about 20F different from the top of the melt in my Lee 20# to the bottom, nearer to where the heating element is. The heating element on my pot is about an inch above the bottom and the melt temp is understandably a few degrees hotter there on the sides of the pot than it is at the center bottom of the pot. Point is, the IR thermo won't tell you what the temp is at the point you're drawing your alloy from in the pot. Ya gotsta get the thermo down into the mix.

Regards,

Stew

[Sundogg1911]

AZ-Stew,
There are only 2 issues I have with the Lee pots. The first one is the dreaded drip, drip drip. which I can live with, the other is as the alloy lowers in the pot, i'm always backing off the temp. The heating element is on the bottom. even though I am always stirring, I wonder if i'm getting an accurate reading with my Lyman thermometer. For the price though, i'll live with these few issues.

[tomf52]

Floodgate - When using your infared on this freshly skimmed surface of the pot were you holding the thermometer 90 deg perpendicular to the surface? If held at an angle the refectivity would be compromised.

[floodgate]

tomf52:

No, it was at an angle; I'll give it a try held vertically next time I've got a pot-full all melted and skimmed, and comare it with the thermometer.

floodgate

[AZ-Stew]

Sundog1911,

My Lee 20# started its life relatively drip-free, but after a few sessions it started leaking (I think my 10# leaked from day 1). I suspect it's due to alloy impurities accumulating around the valve seat. Someone on this list mentioned improving the valve seat by putting valve grinding compound on the valve rod and running it in a drill in the pot spout to increase the valve seat area. I may try it. Can't hurt.

As to the temperature swings, this issue bothers me a bit, as well. Mine swings pretty widely. I'm considering the mod someone else posted here to add a digital temperature control to the pot. A thermocouple is fixtured to the bottom center of the pot and connected to the control unit (PID?) which, in turn, controls a relay that connects/disconnects the power to the heating element. It's a far more precise arrangement than the stock mechanical thermostat, and can be done for about $75, making a well controlled pot for a price that is still far below the other manufacturers' offerings. I may take a crack at it, as well.

Regards,

Stew

[vmt_hntr]

Before I retired, I acquired 2 digital heat controllers(will go well beyond 1000 degrees F) and 2 thermocouples that were used for the solder pots there for tinning lead wires for transformers.(being an electrician, it didn't hurt a thing that I also maintained the solder pots as well) The name on theses units was Barber-Colman...big on heat controllers...and quite pricey($500 each)...was headed for the scrap heap or auction, so my buddies in calibration department fixed me up after one operation we had went south. Boy, it sure works swell for my Lyman 20# pot....the original controller didn't last very long. No tellin' how long they will last, but have been going strong for 6 years now on the original set-up...not had to use the back-up set. The thermocouple is directly in the melt held by a bracket I made that mounts off to the side of the flat surface surrounding the pot. The 'couple is then plugged into the control box that holds the control relay and digital thermometer that supplies power to the heat element which also plugs into the control box. I can keep my pot/melt temperature within 10 degrees of what I need for consistent casting. The weak link I have found is the terminals where the incoming wire and heat element join. Seems to burn that wire in two every so often(it's an easy fix). I know not every one can acquire things like I have, but being in the right place at the right time goes a long way. Happy casting....Bob in Indiana

[Sundogg1911]

vmt hntr,
I'm looking into doing this (Since the company I work for used to be part of Barber Colman) I know we have some of these units back in the test/repairs dept.
I work more in the business end of the company, not the technical side, but I have a few friends there trying to hook me up with the parts that I need.
this would make the Lee pot very usuable, instead of always using the pot on the master caster, and locking down the mold carrier. The slight dripping I can live with.